cheat-fork-echo/cheat

232 lines
8.6 KiB
Python
Executable file

#!/usr/bin/env python
"""
cheat.py -- cheat allows you to create and view interactive cheatsheets on the
command-line. It was designed to help remind *nix system
administrators of options for commands that they use frequently,
but not frequently enough to remember.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
"""
import os
import sys
import argparse
import subprocess
from textwrap import dedent
DEFAULT_CHEAT_DIR = os.environ.get('DEFAULT_CHEAT_DIR') or \
os.path.join(os.path.expanduser('~'), '.cheat')
USE_PYGMENTS = False
# NOTE remove this check if it is confirmed to work on windows
if os.name == 'posix' and 'CHEATCOLORS' in os.environ:
try:
from pygments import highlight
from pygments.util import ClassNotFound
from pygments.lexers import get_lexer_for_filename, TextLexer
from pygments.formatters import TerminalFormatter
USE_PYGMENTS = True
except ImportError:
pass
def pretty_print(filename):
"Applies syntax highlighting to a cheatsheet and writes it to stdout"
try:
if os.path.splitext(filename)[1]:
lexer = get_lexer_for_filename(filename)
else:
# shell is a sensible default when there is no extension
lexer = get_lexer_for_filename(filename + '.sh')
except ClassNotFound:
lexer = TextLexer()
with open(filename) as istream:
code = istream.read()
fmt = TerminalFormatter()
highlight(code, lexer, fmt, sys.stdout)
class CheatSheets(object):
dirs = None
sheets = None
def __init__(self):
self.dirs = self.__cheat_directories()
# verify that we have at least one cheat directory
if not self.dirs:
error_msg = 'The {default} dir does not exist or the CHEATPATH var is not set.'
print >> sys.stderr, error_msg.format(default=DEFAULT_CHEAT_DIR)
exit(1)
self.sheets = self.__cheat_files()
def __cheat_directories(self):
"""Assembles a list of directories containing cheatsheets."""
default_directories = [DEFAULT_CHEAT_DIR]
try:
import cheatsheets
default_directories.append(cheatsheets.cheat_dir)
except ImportError:
pass
default = [default_dir for default_dir in default_directories
if os.path.isdir(default_dir)]
if 'CHEATPATH' in os.environ and os.environ['CHEATPATH']:
return [path for path in os.environ['CHEATPATH'].split(os.pathsep)
if os.path.isdir(path)] + default
else:
return default
def __cheat_files(self):
"""Assembles a dictionary of cheatsheets found in the above directories."""
cheats = {}
for cheat_dir in reversed(self.dirs):
cheats.update(dict([(cheat, cheat_dir)
for cheat in os.listdir(cheat_dir)
if not cheat.startswith('.')
and not cheat.startswith('__')]))
return cheats
def edit(self, cheat):
"""Creates or edits a cheatsheet"""
# Assert that the EDITOR environment variable is set and that at least 3
# arguments have been given
if 'EDITOR' not in os.environ:
print >> sys.stderr, ('In order to create/edit a cheatsheet you '
'must set your EDITOR environment variable to your favorite '
'editor\'s path.')
exit(1)
elif os.environ['EDITOR'] == "":
print >> sys.stderr, ('Your EDITOR environment variable is set '
'to nothing, in order to create/edit a cheatsheet your must '
'set it to a valid editor\'s path.')
exit(1)
else:
editor = os.environ['EDITOR'].split()
# if the cheatsheet already exists, open it for editing
try:
if cheat in sheets.sheets:
subprocess.call(editor + [os.path.join(self.sheets[cheat], cheat)])
# otherwise, create it
else:
import cheatsheets as cs
# Attempt to write the new cheatsheet to the user's ~/.cheat dir if it
# exists. If it does not exist, attempt to create it.
if os.access(DEFAULT_CHEAT_DIR, os.W_OK) or os.makedirs(DEFAULT_CHEAT_DIR):
subprocess.call(editor + [os.path.join(DEFAULT_CHEAT_DIR, cheat)])
# If the directory cannot be created, write to the python package
# directory, though that will likely require the use of sudo
else:
subprocess.call(editor + [os.path.join(cs.cheat_dir, cheat)])
except OSError, e:
print >> sys.stderr, ("Could not launch `%s` as your editor : %s"
% (editor[0], e.strerror))
exit(1)
def list(self):
"""Lists the cheatsheets that are currently available"""
max_command = max([len(x) for x in self.sheets.keys()]) + 3
return ('\n'.join(sorted(['%s [%s]' % (key.ljust(max_command), value)
for key, value in self.sheets.items()])))
# Custom action for argparse
class ListDirectories(argparse.Action):
"""List cheat directories and exit"""
def __call__(self, parser, namespace, values, option_string=None):
print("\n".join(sheets.dirs))
parser.exit()
class ListCheatsheets(argparse.Action):
"""List cheatsheets and exit"""
def __call__(self, parser, namespace, values, option_string=None):
print sheets.list()
parser.exit()
class EditSheet(argparse.Action):
"""If the user wants to edit a cheatsheet"""
def __call__(self, parser, namespace, values, option_string=None):
sheets.edit(values[0])
parser.exit()
def main():
global sheets
sheets = CheatSheets()
desc = dedent('''
cheat allows you to create and view interactive cheatsheets on the
command-line. It was designed to help remind *nix system
administrators of options for commands that they use frequently,
but not frequently enough to remember.''').strip()
epi = dedent('''
Examples:
To look up 'tar':
cheat tar
To create or edit the cheatsheet for 'foo':
cheat -e foo
To list the directories on the CHEATPATH
cheat -d
To list the available cheatsheets:
cheat -l
''').strip()
parser = argparse.ArgumentParser(prog='cheat',
description=desc, epilog=epi,
formatter_class=argparse.RawDescriptionHelpFormatter)
parser_group = parser.add_mutually_exclusive_group()
parser_group.add_argument('sheet', metavar='cheatsheet',
action='store', type=str, nargs='?',
help='Look at <cheatseet>')
parser_group.add_argument('-e', '--edit', metavar='cheatsheet',
action=EditSheet, type=str, nargs=1,
help='Edit <cheatsheet>')
parser_group.add_argument('-l', '--list',
action=ListCheatsheets, nargs=0,
help='List all available cheatsheets')
parser_group.add_argument('-d', '--cheat-directories',
action=ListDirectories, nargs=0,
help='List all current cheat dirs')
args = parser.parse_args()
sheet = args.sheet
# Print the cheatsheet if it exists
if not sheet or sheet in ['help', 'cheat']:
parser.print_help()
elif sheet in sheets.sheets:
filename = os.path.join(sheets.sheets[sheet], sheet)
if USE_PYGMENTS:
pretty_print(filename)
else:
with open(filename) as istream:
for l in istream:
sys.stdout.write(l)
# if it does not, say so
else:
print >> sys.stderr, ('No cheatsheet found for %s.' % sheet)
exit(1)
exit()
if __name__ == '__main__':
main()